Method of controlling gas or vapor electric lamps.



No. 682,695. Patented Sept. I7, 190i.

P. C. HEWITT. METHOD OF CONTROLLING GAS 0R VAPOR ELECTRIC LAMPS.

(Application filed Tan. 25, 1901.)

(No Model.)

- by (EM-1 AM 411% "m: uonms mans co. Pummm'yn. wiuumurou. n. c.

UNITED STATES PATENT OFFICE.

PETER COOPER HEWITT, OF NEW YORK, N. Y., ASSIGNOR TO PETER COOPERHEWITT, TRUSTEE, OF SAME PLACE.

METHOD OF CONTROLLING GAS 0R VAPOR ELECTRIC LAMPS.

OPECIFICATION forming part of Letters Patent N 0. 682,695, datedSeptember 17, 1901.

Application filed January26, 190l- Serial No. 44,647. (No model.)

To all whom it 71mg concern:

Be it known that I, PETER COOPER HEWITT, a citizen of the United States,and a resident of New York, in the county of New York and State of NewYork, have invented certain new and usefulImprovementsin Methods ofControlling Gas or Vapor Electric Lamps, of which the following is aspecification.

My invention relates to a method of producing light by means ofelectricity traversing a gas or vapor, the special object of theinvention being to control the electrical conductivity or resistance ofthe gas or vapor by means which will be described in the presentspecification.

I have found that under proper conditions a gas or vapor inclosed withina suitable vessel or container can be made to control the flow ofcurrent under the influence of a given difference of electricalpotential through the medium of its resistance. I have also found thatthe electrical resistance of a conducting :gas or vapor bears a definiterelation to the density of the gas or vapor. I have further found thatit is possible so to control the density of an inclosed gas or vaporacted upon by an electric current as to maintain that density at apredetermined degree, rendering its conductivity sufficiently stable andsuitable for service as a light-giving medium, its

efficiency in that respect being exceedingly .great.

h/Iyprescntinvention aims to provide means I for such control of thedensity of (the gas or vapor which is acted upon by the current' fiowing as to render its naturally-variable resistance controllable andstable, and thereby produce a highly efficient and commercially usefulelectric-lighting device.

I have'foundthat the conductivity of a conducting gas or vapor increasesas its density decreases up to a certain limit, beyond which decrease ofdensity the conductivity diminishes with further attenuation of the gasor vapor. Starting from the condition of maximum conductivity, in otherwords, the resistance increases as the result of either an increase or adecrease of the vapor density. The first step toward controlling thedensity of the gas or vapor is taken when it' is inclosed in a containerof definite volume.

When the gas or vapor has been so inclosed, the density of theconducting-path may then be varied by providing outside this path onevor more chambers into which a portion of the gas or vapor can be madeto pass or by the condensation or volatilization of suitable materialheld within the container. The total density is a function of thepressure (as determined by the limits given to 'the container throughits length and radius) divided by the temperature. The density in anyselected portion of the vapor inside the container depends upon thetemperature of that portion as modified by the pressure affecting thatportion. The effect of temperature in decreasing the density in aportion of the container by attenuating the vapor may be in partcorrected by an increase in pressure.

In an operating lamp the active agent which can be relied upon forproducing the eifects of light and heat is the current. In constructingan electric vapor-lamp designed for service as an efficient light-givingmedium the object should be to provide means for so controlling theefiects of the current as to make the lamp self-regulating, so that theheat developed by the current shall vary the density of the vapor andincidentally the pressure, the Whole being accomplished in dius of thecontainer, but also throughproperly selecting the thickness of the wallsand in some instances providing one or more special cooling-chambers forassisting in the radiating of heat, Inasmuch as the radiation of heattakes place at the circumference the temperature of a vapor throughwhich an electric current is flowing must necessarily vary throughoutfrom circumference to center, being highest at the center and lowest atthe circumfergnce. Accordingly a vapor car- To a rying current will havea varying density, decreasing along the radius from the circumference tothe center. If now the density of the vapor in the container, where nocurrent is passing, is at or below the density of maximum conductivity,the zone which nearest approaches the state of maximum conductivity whencurrent is permitted to pass will be at the circumference, the vaporresistance increasing along the radius from the circumference to thecenter inversely as the density due to the attenuation caused by heatfrom the current. When the density of the vapor in the container isgreater than the density of maximum conductivity, the vapor resistancewill decrease along the radius of the conducting-column from thecircumference to a point Where the vapor is attenuated to the density ofmaximum conductivity, and from that point to the center the density willbe below the state of maximum conductivity, and consequently the vaporwill be of greater resistance toward the center.

If we adopt such a density of the contained gas or vapor that the zoneof maximum conductivity or the zone nearest approaching that state is atthe circumference of the vapor, we run the danger of exposing thesubstance of the container to injury from the efiects of the current,and in practice I have found that it is not advisable to expose thecontainer to this danger; but I have also found that with a vapor whosetotal normal density when no current is passing is at or below thecondition of maximum conductivity I can select a radius sufficientlylarge to cause the accumulated vapor at the circumference due to theheat developed when the current begins to fiow to have a resistancegreater than that of maximum conductivity, whereby the conditionmentioned in the preceding paragraph is attained, or I can select aradius large enough so that the heat generated by the current will notendanger the container. Thus it will be seen that the best availableworking condition for a lamp of this class is generally one in which thedensity is somewhat above the state of maximum conductivity. In thiscondition the zone of greatest conductivity is an annulus located alongthe radius between the center of the contained tube or chamber and theinner wall thereof. Bearing in mind that the conductivity of the gas orvapor is greatest at a given density J or attenuation, the fact notedindicates that the stratum of gas or vapor between the inner surface ofthe wall and the so-called conducting zone is of greater density thanthat of maximum conductivity. The successful operation of a gas or vaporlamp appears to depend upon the proper control of the density of thisouter stratum, thus determining the pressure of the said stratum uponthe conducting zone and controlling the total conductivity of the lamp.The gas or vapor density in various parts of the container is governedby the temperature of the conducting rate of heat radiation or heatemission therefrom per degree of difference of temperature. As in otherelectric lamps, the real controlling agent in a gas or vapor lampconstructed to be used at a constant voltage is primarily theresistance; but inasmuch as the resistance of a gas or Vapor dependsupon its density, and as the density depends on what may be called theresultant temperature due to the differential effects of the heatdeveloped by the current and the heat radiated or emitted by the lamp,the controlling agent in a lamp of this class is practically the ratioof temperature of the gas or vapor as influenced by the pressure to theheat-dissipating capacity. If this temperature can be maintaineddefinite at predetermined pressure, the ratio of density will bedefinite, and hence the conductivity or the resistance of the conductingmedium will be definite with respect to a definite current. In lampswherein a vapor is produced by the Volatilization of a suitablesubstance contained within the tube or chamber the same law holds good,bearing in mind that the density may in crease with the temperature,although in such cases the relation of the volatilizing or boil= ingpoint of the substance employed to the temperature at which it isintended to 0p crate must be taken into consideration. In such lamps aproperly-selected vapor temper ature maintained by the regulation of theheat emission will accord approximately reliable self-regulation, thesupply of fresh vapor to compensate for the condensation resulting fromany cooling process being automatically responsive to the demands ofoperation. It follows that a lamp of this character in order to bestable should be so constructed that when the density of the gas orvapor has reached the point thatis best suited for practical operationthe rate of emission of heat from the lamp should be the same as therate of development of heat caused by the passage of the current. Inother words, the gas or vapor employed as the conducting medium shouldbe confined in such a manner and with such surroundings that the thermalconditions inside the containing tube or chamber shall remain unchangedor shall correct themselves under varying conditions of imparted heatdue to a varying flow of current at any given time. Should theheatradiating capacity of the lamp be either too great or too small withrespect to the current, the resultant temperature would cease to be acorrective factor and the vapor density and lamp resistance would beunstable and the lamp would cease to be self-corrective in its action.

In accordance with what has been suggested above, self-regulation inlamps of this class may be attained by subjecting the gas or vaporpathto such surrounding conditions as to secure the radiation or emission ofheat at a predetermined rate, or means may be provided in addition tothe regula tion of the heat emission for supplying additional vapor, asfrom vaporizable material, to the conducting medium as the density ofthe vapor-path tends to become too attenuated and so have a tendencytoward increasing the density due to increase of temperature by thismeans instead of decreasing density.

In the accompanyingdrawings I have illus- I trated several forms andarrangements of gas and vapor lamps adapted to serve for carrying out myinvention.

In the drawings, Figure 1 is a section of a lamp adapted to contain asuitable gas the densityof which will decrease with an increase oftemperature. Fig. 2 is a similar view of a lamp in which the gas willmaintain a constant total density. Fig. 3 represents in section avapor-lamp containing a volatilizable substance, and so arranged thatthe density will increase with an increase of temperature. Fig. 4similarly represents a vapor-lamp wherein the density of the vaporvaries in a prescribed manner with the temperature. Fig. 5 represents avapor lamp with variable vapor density, the same being surrounded by atransparent jacket provided with means for adjusting the amount of heatabstracted at a given time; and Fig. 6 is a similar view of a lamp withconstant density surrounded by a transparent jacket with a variabledraft to enable varying the temperature the lamp my attain.

In Fig. l the main portion of the container is represented by a tube 1,within which are held two electrodes 2 and 5, of pure iron, the formerof which may represent the anode and the latter the cathode. At each endof the tube 1 in this figure I have represented a bulb or enlargement 4extending beyond the electrodes in such a manner that the gas containedin these bulbs will be mainly outside the conducting-path between theelectrodes. The contained gas may be a mercury vapor or nitrogen orother suitable gas. Conductors 7 and 8, of platinum, leading to theelectrodes 2 and 5, respectively, are sealed through the glass andcovered for a considerable distance inside the container with glass orother good heat-resisting non-conducting material. Generally thecovering of such material will extend as far as the electrodes, asillustrated at 10 10. In. the operation of this lamp a portion of thegas or vapor is forced into the bulbs or enlargements 4 4, thus bringingabout a condition of variable density within the lamp due to theattenuation caused by the heat of the current.

In Fig. 2 I illustrate a lamp of constanttotal density at all workingtemperatures. In this lamp the bulbs or enlargements are dispensed withand practically all of the gas or 'vapor is in the conducting-path. Thegas or vapor may be a mercury vapor or nitrogen or other suitable gas.

The lamp illustrated in Fig. 3 has as its cathode some volatilizablematerial, as shown at 5. This material may be a puddle of mercury. Inthis form of lamp the density of the vapor will increase with thetemperature, although the cooling-chamber 4 may serve to condense aportion of the vapor.

Fig. 4 illustrates a modification of the lamp shown in Fig. 3, wherebythe density may be made to vary in a prescribed manner with thetemperature through giving to the enlargements 4 4 a definite containingand heat-radiating capacity, the enlarged portions lying outside theconducting vapor path.

In'Fig. 5 I show a vapor-lamp containinga volatilizable material, theentire lamp being surrounded bya transparent jacket 18, closed at thebottom and having openings 19 19,-

vwith which similar openings 25 in an adj ustable ring 21 are adapted tomesh when moved to the proper position. The jacket 18 is suspended froma cap 22, through, which the 1eading-in wire 7 passes on its way totheelec-' trode 2. The cap 22 may be secured to the wire 7 by any suitablemeans, as by the sealing of the wire into the cap. The connectionbetween the cap and the jacket may be made by means of screws 23 '23,passing through the cap and engaging with a head or beads 24 on thejacket. Where the screws pass through the material of the cap, pieces ofmetal 25 25 may be secured to the cap in order to hold the screws, or aband or ring of metal may be secured to the cap for the same purpose.'The upper end of the jacket 18 is open, and within limits any desireddraft may be maintained between the lamp proper and the jacket throughthe regulation of the openings 19 by means of the ring 21. Fig. 6 showsa similar draft-varying device in connection with a lamp similar to theone illustrated in Fig. 2. In this arrangement, however, the draft isregulated at the lower end by the adjustment'in a vertical direction ofa cap or end piece 26 through the medium of screw-bolts 27 27, passingthrough suitable flanges 28 28 on the lower end of the jacket 18 and onthe cap or endpiece 26.

The principles laid down in the present specification are embodied'inpractical form in a lamp in which the container is of glass, having abore three-quarters of an inch in diameter, the length between theelectrodes being fifty-four inches and the chamber lying outside of thepath of the current having a radiating-surface equal to a spherical areathree inches in diameter. The positive elec trode will be'constructed ofpure iron held in place by a supporting-pillar of glass, through whichthe platinum leading-in wire passes.- The negative electrode may be apuddle of mercury, as shown, and a platinum leading-in wire extendingthrough the walls of the vessel will connect the mercury with theexternal cir cuit. Such a lamp will run on a current of approximatelyone hundred and twenty volts and pass approximately four amperes whenthe surrounding temperature is that of an ordinary roomsay seventy-fivedegrees.

The above is given merely as an illustrative lamp. By varying theproportions and dimensions the current consumed by the lamp may bevaried from the above within wide limits, and the lamp may be made toadapt itself to the conditions of any circuit, and the lamp may beconstructed to run on constant-voltage circuits of wide range ofvoltage.

The lamp may be started by any of the devices such as are described, forexample, in

my pending application, Serial No. 11,605, filed April 5, 1900.

The foregoing specification relates, primarily,to means for controllingthe conductivity or resistance of a gas or vapor lamp by the meansdescribed, the object being to maintain a uniform resistance orconducting power under generally uniform conditions of outsidetemperature, as when a lamp of this sort is intended to give light in aconfined space. It is possible, however, by varying the externaltemperature through such means as are illustrated, for example, in Figs.5 and 6, or by any other simple means, to produce the same conditions ofstability under a constant lower temperature; but in that case the lampresistance will be decreased while the current is increased, as well asthe candle-power of the lamp, the electromotive force remainingstationary. Having selected some lower outside temperature, therebycausing a more rapid radiation of the heat, the lamp will regulateitself in the manner hereinbefore described so long as the outsidetemperature remains at the lower degree. These principles furnish ameans for increasing or decreasing the brilliancy of the light emittedby a lamp of this class without impairing its efficiency, as the wattsconsumed are varied by varying the actual resistance of the lamp itself,as will be readily understood.

In certain other applications filed by mefor instance, Serial Nos.11,605, 11,606, and 11,607, filed April 5, 1900, and Serial Nos. 44,648and 44,649, filed January 25, 1901 claims are made to certain featureswhich are disclosed herein.

I claim- 1. The method of maintaining an approximately definiteresistance on the part of a lamp having a vapor or gas path, whichconsists in heating the gas or vapor, by the passage of the electriccurrent therethrough, to such a temperature that the region of greatestconductivity is between the axis of the path and the circumferencethereof, and producing a rate of heat radiation equal to that of theheat development at a predetermined temperature.

2. The method of producing light by the passage of current through a gasor vapor path, which consists in generating heat by the passage ofelectric current through the vapor or gas path, thereby modifying thedensity of the vapor or gas, and maintaining that density at therequired degree by radiating heat therefrom at the same, orapproximately the same, rate as heat is developed therein by regulationof the surroundings.

3. The method of controlling the resistance of an electric lamp having aVapor or gas path and a definite heat-radiating capacity, which consistsin passing current through the vapor or gas path thereby generatingheat, and radiating the heat thus developed at such rate as to maintainthe temperature and thereby the vapor density at a predetermined degree.

4. The method of controlling the resistance of an electric lamp having aVapor or gas path and a definite heat-radiating capacity, which consistsin passing electric current through the gas or vapor in such quantity asto develop heat within the limits of the heat-radiatin g capacity of thelamp, and thereby maintaining the temperature and the vapor density at apredetermined degree.

The method of controlling the resistance of an electriclamp having avapor or gas path, and a definite heat-radiating capacity, whichconsists in mutually correlating the current flowing and the heatradiated by the lamp so as to maintain a predetermined vapor or gasdensity in the conducting-vapor, whereby the rate of heat radiation fromthe lamp is made dependent upon the resistance offered by the vapor orgas path, to the current flowing.

6. The method of operating electric gas or vapor lamps of the characterdescribed, which consists in governing the resistance of the lamp by thedensity of the vapor or gas path, governing that density by thetemperature thereof, and governing such temperature by the heat-emissivecapacity of the lamp.

'7. The method of operating a gas or vapor lamp of the characterdescribed, which consists in governing the current flowing therethroughby the resistance of the lamp, governing the resistance by the vaportemperature, and controlling the vapor temperature by the heat radiationof the lamp.

8. The method of controlling the current flowing through a gas or vaporlamp of the character described, which consists in controlling thetemperature of the lamp by predetermining the heat radiating capacity,thereby controlling the density of the gas or vapor path and therebycontrolling the resistance of the gas or vapor path, whereby the currentflowing is controlled at definite voltage.

9. The method of controlling the varying resistance of a vapor carryingcurrent, which consists in maintaining the heating efiect of the currentapproximately constant by means of varying the heat-abstracting power ofthe surroundings in direct ratio to the current passed.

10. The method of varying the current passed by an inclosed vaporpassing current at Constant voltage, which consists in varying theheat-abstracting power of the surroundtained gas or vapor that thecooling effect of the chamberwill equal the heat-absorbing capacity ofthe gas or vapor for a determined temperature. 1

12. The method ofproducing and maintaining light by the passage ofelectric current through a gas or vapor path, which consists inconfining the gas or vapor within definite limits suited to the densityto be maintained, modifyingthe density of the gas or vapor by thepassage of the current until a suitable operating density is obtained,and maintaining the density at the required degreeby radiating heat fromthe gas or vapor at the same or approximately the same rate as heat isdeveloped therein ata definite temperature.

13. The method of producing and maintaining light by the passage ofelectric current through a gas or vapor path, which consists in heatingthe gas or vapor by the passage of the current and thereby modifying thedensity until a suitable operating temperature isobtained, andmaintaining such density by giving to the lamp a capacity for radiatingheat from the gas or vapor at approximately the same 'rate as heatisdevelo'ped therein at said temperature.

14. The method of adapting a gas or vapor to pass electric current on aconstant-potening light by the passage of electric current through a gasor vapor path, which consists in developing heat by the passage ofthecurrent through the gas or vapor and nullifying or offsetting theheat developed by the passage of the current after the limit ofefficient 1 operation has been reach-ed by the radiation of heat atanequal rate through a proper di- 5 me'nsioning and disposition of thesurround-- ing parts.

16. The method of producing and maintaiu- 3 ing light by the passage ofelectric current at definite voltage through a gas or vapor path f"which consists in first confining the gas or vapor within a containerof appropriate heat- I radiating capacity; producing in the gas or vapora density suitable for efficient working and then causing the thermalconditions Within the gas or vapor to operate automatthe densityselected. Y

ically in opposition to anabnormal change of:

1.7. The method of'controlling the resist-k ance of a gas or vapor lamp'for increasing or decreasing the lightingcapacity of the lamp, whichconsists in varying the heat-abstracting capacity of thesurroundings ofthelamp andtherebyvaryingthecurrentconsumption.

18. The method of producing light, which consists in inclosing a gas orvapor within such limits as to predetermine its normal density as suitedto a definite current, andrende'rin'g the vapor light; radiant by thepassage of electric current to which it is'adapted.

- 19. The method of producing light,which consists in inclosing avapor-producing material within such limits as to predetermine thenormal density as suited to a definite current, creating a vapor fromsuch material by heat, and rendering the saidvapor light m.

diant by the electric current to which. it is' adapted.

20. The method of producinglightywhichconsists in in'closing a vaporwithin such limits as will produce a normal density adapted to give it adefinite lowresistance, and passing through such vapor, as the soleconducting medium, acurrent of electricity of considerable quantity andof a voltage adapted to the resistance of the vapor.

21. The method of producing light, which within such limits as willgiveto the produced vapor a normal density adapted to produce lowresistance, passing an electric current through the said agent tofirstproduce vapor of the normal density from it and thenbringing saidvapor into a light-radiant condition by means of electricity.

23. The method of producing light, which consists in inclosing avolatilizable substance within such limits as Will cause the vaporproduced therefrom to be of a density near its point of lowestresistance to an electric current, subjecting the substance to heat andthereby developing vapor, and passing into the Vapor an electric currentof low voltage.

24. In the production of light, the method of removing vaporousimpurities from a light-' radiant inclosur-e, whichconsists involatilizin g an inolosed vapor-producin g agent by the passage of anelectric current, and permitting the vapor so formed to drive vapor-ous,impurities in the inclosure to a pointoutside the influence of thecurrent.

v25. The method of causing an incipient IIO ' the vapor in a containerof predetermined dimensions with respect to the current and so having adefinite heat-radiating capacity, and causing the current to createvarying densities in different parts of the container due to the heatingeffect of the current.

27. The method of controlling the current passed at constant voltage bya vapor carrying current, which consists in inclosing the vapor, passingcurrent therethrough, thereby developing heat therein, and so adjustingthe surroundings that-the density of the vapor carrying current indifferent parts of the container Will vary With variations in thecrosssection of the vapor traversed by the current.

28. The method of securing the control of the current passed. by aconducting-vapor at constant voltage, which consists in limiting thecross-section and length of the conducting-vapor, therebypredeterinining the heatradiating capacity of the apparatus, and causingthe resistance of the vapor to vary by reason of the ratio of the heatgenerated by the current to the rate of heat radiated by the Vapor tothe surroundings.

Signed at New York, in the county of New York and State of New York,this 24th day of January, A. D. 1901.

PETER COOPER I'IEVIT".

\Vitnesses:

WM. H. CAPEL, GEORGE II. STocKBnmoE.

